Some thermostats, like the Ecobee wi fi stat, have some open connectors that could have sensors like a wet switch or open doors, added to them. A wi fi stat can send you an email if the sensor switch is tripped.

I'm more looking for the physical device that shuts off the water if a leak is detected.

I think that'll be the first/main line of protection.

I recently had a pretty major flood. I'm not sure exactly what happened, but a taco valve malfunctioned and somehow water was pouring out of the safety release for some time.

I'd like to have some way of preventing that from ever occurring again.

What's the best way (reasonably priced) to protect myself?